[The natural history of renal angiomyolipoma]

To make the policy of treatment with angiomyolipomas (AML) more clear, we discussed the natural history of angiomyolipomas retrospectively.

Between May 1982 and December 1997, 14 patients with AML in 18 kidneys were followed, who were 2 men in 2 kidneys and 12 women in 16 kidneys, 27 to 80 years old. No patients suffered from tuberous sclerosis. Symptoms, initial sizes and changes of the size were evaluated for these patients.

Ten patients with AML in 14 kidneys were asymptomatic and four patients were symptomatic. But one of the 4 patients had symptoms of abdominal pain and palpable mass which were due to contralateral AML that were treated with nephrectomy, so symptoms due to small AML were seen in 3 cases (2.0 cm, 3.5 cm, 3.8 cm). Among 11 patients in 15 kidneys followed radiologically for more than 6 months, the tumors were unchanged in size in 7 kidneys, which were in all of 6 cases with unilateral solitary tumor and in 1 with bilateral multiple tumors. In other 8 kidneys the sizes of the tumors were increased, which were in the cases with multiple tumors in one kidney or in bilateral cases. Compared to the cases of unilateral solitary AML, the size of AML with multiple tumors in one kidney or in bilateral kidneys significantly increased (p < 0.01). Embolization were performed for 4 kidneys, which were in 2 cases with increased tumor in size to more than 4 cm in following period, in 1 with dull flank pain, and in 1 with the tumor more than 4 cm at diagnosis that grew to more than 5 cm.

Unilateral solitary AML was appeared to be hard to increase in size and to have a different natural history from bilateral or multiple tumors.